Frankly, they all sound good to me; I hope that doing one doesn't mean you'll discard the other ideas!
I'm going to put in a word for #1. Its biggest weakness is also its biggest strength--namely, that it's a straightforward mission. It might be called generic, but that also means it's adaptable to almost any group and can easily be dropped into someone's homebrew game world.
I also like #2 (interesting opportunities for roleplay and investigation) and #4 (could be nicely creepy with all the undead and revenge).
I'm going to put in a word for #1. Its biggest weakness is also its biggest strength--namely, that it's a straightforward mission. It might be called generic, but that also means it's adaptable to almost any group and can easily be dropped into someone's homebrew game world.
I also like #2 (interesting opportunities for roleplay and investigation) and #4 (could be nicely creepy with all the undead and revenge).